TYPE: U.S.A. TEXAS: Travis Co: Austin, Colorado River gravel, just below Montopolis Bridge (ca. 100 m upstream on small, mid-stream islet). Only one plant found growing at the site concerned. Area revisited one week later by Bob Corbin and Bill Carr; no additional plants were found in spite of extensive search. Indeed, the remnants of the original plant had also been pulled up by the roots, according to Corbin, who located the hole left by its extrication. Who removed the plant is not known. Perennial robust herb or subshrub to 2 m high, just beginning to produce flowering branches. Roots seemingly tap-rooted, w/o rhizomes or runners. 15 Jul 2008, Robert Corbin s.n. (Holotype: TEX).

Ivae axillari Pursh similibus sed differt plantis elatioribus et phyllariis externis distinctis ad basibus (vs. connatis).

Perennial tap-rooted herbs up to 2 m high. Mid-stems 0.4–0.8 cm thick, more or less striate with thickened ribs, pubescent with upwardly-appressed, broadbased hairs ca. 0.5 mm long, among these a scattered array of yellowish globules; lowermost stems up to 2.5 cm across. LEAVES of flowering branches alternate, 6–7 cm long, 2.0–2.5 cm wide; petioles 1.5–2.5 cm long; blades oval, widest at or near the middle, 3-nervate from the base, grading into the petioles, apically acute, the margins entire; leaves of earliest or lowermost branches variously ovate to broadly deltoid. HEADS borne single and nearly sessile in the leaf axils. Involucres 3–4 mm high, 5–8 mm across; bracts 3–5, broadly ovate, sparsely short-pubescent and glandular, rounded at the apices, ca. 4 mm long, 4–6 mm wide, separate to the base; chaff oblanceolate to ovoid. Pistillate florets 2–3, fertile; corolla ca. 1.5 mm long, eligulate; style braches linear-lanceolate, ca. 1.3 mm long. Staminate florets 5–10; corolla ca 2.5 mm long. Achenes black, minutely rugose, ca 2.5 mm high, 2.8 mm wide, glabrous or nearly so.

Additional collection examined: TEXAS. Travis Co.: Austin, just west of Del Valle where Hornsby Bend Road (Highway 973) crosses the Colorado River, ca. 100 m below bridge on soggy islets. Soggy silty-clay soils, growing among a dense array of perennial herbs and subshrubs, including Polygonum, Verbena, Sesbania, Ambrosia trifida, 27 Jul 2008, B.L. Turner 8-01 [with R. Corbin, M. Turner & P. Waller] (BRIT, SRSC, TEX).

This extraordinary species is a robust herb or sub-shrub to 2 m high. The Hornsby Bend population consisted of ca. 16 individuals scattered over ca 100 square yards. So far as could be determined, the plants were seemingly tap-rooted, lacking rhizomes or runners.

It is possible that the present novelty might best be positioned in a novel genus, so different it is from previously described species of Iva (cf. Strother, 2006). I positioned it in the latter because, were the leaves reduced to bracts the capitulescence would resemble that of a typical flowering branch of an Iva (e.g., I. axillaris Pursh). In short, I take the taxon to be a primitive or basal element of the genus Iva. But the DNA data, as assembled by Maio et al. (1995), might ultimately prove me wrong. Such work needs to be done.

The species is named for its first collector, Mr. Robert Corbin (Fig. 2), exceptional naturalist and citizen of Austin, Texas. He is an avid explorer of river bottoms, recording the occurrence of rare or unusual plants and animals. His curiosity as to the identity of the present novelty paid off “big time.” May his curiosities continue!